AMWA IS-11 NMOS Stream Compatibility Management Specification: Overview
Introduction
The purpose of AMWA IS-11 is to provide a mechanism by which to configure Sources, Flows and Senders using information from Receivers. A Receiver provides Receiver Capabilities and exposes its Outputs, each of which may hold EDID from its downstream counterpart. A Sender has Active Constraints, which restrict media formats allowed for sending, and Inputs, each of which may have an Effective EDID to present to its upstream media producing unit.
The Specification includes:
- RAML and JSON Schema definitions, with supporting JSON examples
- This documentation set, which provides:
- An overview of the API and how it is used.
- Normative requirements in addition to those included in the RAML and JSON schemas specifying the API.
- Additional details and recommendations for implementers of API providers and clients.
- Information about interoperability with other specifications and compatibility between different API versions.
The NMOS Glossary defines several common terms that have specific meanings in NMOS. The terms ‘Node’, ‘Device’, ‘Source’, ‘Flow’, ‘Sender’ and ‘Receiver’ are used extensively in this documentation set. The NMOS Technical Overview provides an outline of these terms, and IS-04 provides corresponding schema definitions.
The terms ‘Parameter Constraint’ and ‘Constraint Set’ used in this documentation set are defined in BCP-004-01.
IS-11 is intended to be used in conjunction with an IS-04, IS-05, BCP-004-01 and BCP-005-01 deployment; however it has been written in such a way to provide useful functionality even in the absence of such a system.
Use of Normative Language
The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this documentation set are to be interpreted as described in RFC 2119.
Terminology
Input
An Input is a logical input connector which consumes video, audio and ancillary data for providing it to Sender(s) through a number of Sources and Flows. The precise relationship between the Inputs and such Sources and Flows is not specified and there may be an IS-08 mapping element in the system. The Input may present metadata about media consuming capabilities to its upstream counterpart. Each Input is a resource and based on Resource Core JSON Schema.
Output
An Output is a logical output connector which produces video, audio and ancillary data provided by Receiver(s). Output may hold metadata about the media consuming capabilities from its downstream counterpart. Each Output is a resource and based on Resource Core JSON Schema.
API Structure
The API provides a mechanism to get information about Inputs associated with Senders and Outputs associated with Receivers and to constrain a Sender from sending a Flow not supported by its subscribers.
The API is divided into the following parts:
Senders
Each Sender has an inputs resource, which lists identifiers of all Inputs associated with this Sender, a constraints base resource which allows controlling the restrictions for the Flow associated with this Sender and a status resource showing the Sender’s state in terms of IS-11.
Constraints
There is an active resource which holds Active Constraints and a supported resource which lists all the Parameter Constraints supported by this Sender.
Receivers
Each Receiver has an outputs resource, which lists identifiers of all Outputs associated with this Receiver, and a status resource showing the Receiver’s state in terms of IS-11.
Inputs
Each Input has a properties resource, which has metadata about this Input, and an edid resource, which may hold EDIDs associated with this Input.
EDID
There is a base resource which holds the Base EDID used by the Input as the basis for creating the Effective EDID.
The effective resource holds the Effective EDID presented to an upstream counterpart of this Input.
Outputs
Each Output has a properties resource, which has metadata about this Output, and an edid resource, which may hold the EDID presented to this Output by its downstream counterpart.